Form for outlining electric-furnace channels



J. R. WYATT.

FORM FOR OUTLINING ELECTRIC FURNACE CHANNELS.

APPUCATION FILED JAN 10. 1918.

'1 ,3 1 3, 5'7 1 Patented Aug. 19, 1919,.

F7 -5 I 39 I .55

. :2 30 v I I I I 2 ig ZZI 593 I 32 vmewtoz Witness.-

UNITED STATES Parana. OFFICE.

JAMES R. WYATT, OI PHILADELPHIA, PENNSYLVANIAyASSIGNOR TO THE AJAX METAL COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION OP PENNSYLVANIA.

To dll whom it may concern: Be it known that I, JAMES R. WYATT, a

citizen of the United States, residing at 2024 S. 21st street, Philadelphia, in the county of Philadelphia and State of Pennsylvanla, have invented a certain new and.

useful Form for Outlining Electric-Furnace Channels, of which the following is a specification.

My invention relates to a form for outlining the resistor channel in an electric furnaee. The purpose of my invention is to protect against injury to'the lining by expansion of the form. I also provide for 16 sintering the adjoining lining material.

A further purpose is to provide a com- I posite form made up of difi'erent materials. A further purpose is to provide a space extending longitudinally of the form and 20 either empty r filled with a-readily removable substan of the form.

A further purpose is to provide a metallic secondary path, used in starting the furnace,

facilitating the destruction V and at the same time relieveagainst undue expansion by interposing a compressible or removable portion to prevent breakage of the refractory lining.-

A further purpose is to give room for expansion of a metallic secondary form,

tak ng care'of either longitudinal or transverse expansion or'both.

A further purpose is to relatively weaken the to of a metallic secondary form so as to ma e that its weakest section.

A further purpose is to practise the process herein set forth.

Further pur oses will appear in the specification an in the claims.

40 I have preferred to illustrate my invention by forms which have been testedby me and which will illustrate the principles of my invention.

Figure 1 is a iside elevation of a type of. 46 furnace Specification of Letters Patent.

Patented Aug. 19, 1919.

Application med January 10, 1918. Serial No. 211,124.

as is shown in Fig. 1 with fillers providing room for expansion. I Figs 3 and l'arev a section upon line 33 and a top plan view, respectively, of Fig. 2.

Figs. 5, 6, 7, 8 and 9 are cross sections of. variant forms taken at any point in the lower part of the resistor and perpendicular to it; for example, at section line 5--5 of ii the drawings similar numerals indicate like parts.

In electric furnaces of the general char' acter indicated in Fig. 1, some form is needed for outlining the channel or path for the molten secondary path. After the lining is rammed about this form it is necessaryvto provide some means of removing the form.

While the full advantage of my invention requires a metallic circuit throughout the channel len h to act as a secondary in drying out an sintering the lining, that portion of my invention which relatesto facilita-ting practlsed by me by the use of a wooden form having a hole throughout its length so that a flame could be driven through, about the angle. It is very desirable to use compressed air and oxygen to maintain the sparkl.

This wood form presents the advantage as compared with solid metal (unrelieved for expansion) that the wood does not injure the lining b expansion whereas the metal stretches an fractures it. It has the disadvantage that being a non-conductor of electricity, the wooden form cannot be used as a secondary to dry out and sinter the adjoining lining. a

I' have obtained part of the advantage of each of these by using a composite form of which one part is metal and the other is removable or compressible to provide for expansion. .It it quite desirable to use a composite section throughout, against both transverse and longitudinal expansion, but even where the cross section of the major channel length is solid metal,

the removal of the form was first relieving the injurious effects of the lengthwise expansion of the form ma be relieved by a combththe form, preferably with the addition of some molten metal, can be used as :1. seconds. for the purpose of sintering the surroun ing lining material and starting the furnace in operation.

In showing my invention in connection with the furnace of my Patent No. 1,201,671 it is my intention to use this type as typical of those furnaces where room for expansion of the metallic form must be allowed in order to prevent breakage of the adjoining refractory; and I recognize that it is applicable to various other forms of furnaces also.

In the illustration an outer furnace j ackc -is shown at 5 connecting with a channel f The latter is provided at the top'and bottom with channel members 8 and 9. The parts,

are connected by bolts 10 passing through cars 11, 12 upon the jacket and shell respectively' The top of the furnace is formed by a separate shell 13 united to the jacket 5 by ears 14 and bolts. 15. The top opening is closed by a plug 16. Thetransformer winding is shown at 17. For further desired detail as to the referred construction of the furnace itsel reference is made to my patent above indicated.

In furnaces of this general character a lining or refractory 18 is used, which may be of any suitable material which will withstand the heat and which is a poor conductor or a non-conductor of electriclty.

I have successfully used an asbestos paste which is rammed to position about the channel form, preferably by a power hammer. The interior shape of the furnace pool may be outlined either by another form or With a shape of channel such as shown in r Fig. 1 a full metal form could not be .heated to any considerable extent Without ex and-.

ing considerably in the direction 0 the lengths of the straight channel parts, with resultant breakage of the refractory. I'

have discovered that the great advantage .of the metal form in permitting drying andsintering of the lining and in supplying a complete metallic starting secondary may be secured without breakage frbm longitudinal expansion by filling out the outer parts of the frame in the direction of the expansion with temporary fillers which will not interfere withthe expansion of the metal into the space originally occupied by the fillers. These fillers in connection with the metal initially fill the-,full-cross section of viously occupied by the fillers for expansion.

Though my form as illustrated might appropriately be called a stirrup and is described in connection with a furnace intended primarily for melting brass or simi lar alloys it is obvious that the contour and section will vary with the shape of the furnace and that the form is suitable also for the use in furnaces handling other materials. For the brass furnace I have found it quite desirable to use a stirrup of brass because it combines the proper electrical resistance and melting point. For convenience, therefore, and in explanation, but not in limitation, I'shall describe this part of my invention as it has been applied to the brassfurnace shown.

In applying the stirrup (whether of solid or composite cross section at other points, as hereinafter discussed) within the furnace casing the form is first desirably waxed in order to fill up any interstices or irregularities to which the refractory material might adhere and to provide the space occupied by the wax as expansion room when the form is heated. I prefer to make this coating thin and for one type of furnace found a coating of a sixty-fourth of an inch thickness very satisfactory.

The form is held in position by any suitable means, not shown while the liningmaterial is filled in about it and tamped to position. The inner limit may be the transformer winding or a shell 17 thereabout. The placing of the lining within the body of the furnace need not be here described.

For a furnace having V shaped channel as indicated in Fig. 1 thesides 19, 20, of the form, corresponding to the major portion of the channel, are fiat and longitudinal expansion will take place in a straight line, making the total form width between the sides 21,21, wider because of the expansion. For the purpose of allowing room for this expansion I provide fillers 22, 22 which do not show in Fig; 1, having been removed. They have combined thickness at least equal to the amount of expansion in the width of theform, totaling with the addition of the form at each side the thickness ofthe side portion of the channel. I

have obtained excellent results using temporary removable or easily destructible 24, of the stirrup are joined by straps 25,

26, outlining a groove 27 in the bottom of the pool. 'The contour ofthe lining upon the bottom of the groove as at 28 between the straps is given by the. tool used in the power hammer. When the form is put in place the side of the'straps are placed as shown in Fig. 2.

The side fillers 22, 22 take care of the longitudinal expansion but do not relieve from the strain due to transverse expansion of other parts of the form. Across the smaller dimension (generall radial to primary winding) this is small (see Figs. 5 go 8) and I prefer to take care of it wholly y pansion parallel with the axis of the coil, I prefer to use an internal compressible or removable member in addition to the wax, using metal on opposite sides of the center .and some such substance as wax or wood between, which will squeeze out or melt out at -a low temperature or which may be burned out, preferably by a blast before heating the secondary, and which is compressible enough to take care (in connection with the wax or separately) of any expansion which takes place before it is removed or destroyed. I have had much success with a construction of the general character of that shown in section in Fig. 6, taken at the same point as 5-'-5. In this I have used a central portion. 29 of easily compressible,

expressible or removable material, which need not be a conductor of electricity (I have shown wood in Fig. 6, wax 29' in Fig. 8 and a low fusing alloy 29 in Fig. 9, such as described on page 333 of the 4th edition of Kents H aowlboolc) and have preferred to extend this core throughout the length of the channel. On each side of this compressible or readily removable core I show a strip of conducting metal, 30, 30, which may be a mere strip or of substantial section as desired. Where the narrower dimension is also tobe additionally protected a filler of the general character shown at 29 (Fig. 7) may be used with strips 30, 30.

After the lining has been rammed about the form, the refractory is dried out, first at atmospheric temperature and afterward in an oven, and the filler pieces are burned out or otherwise removed, giving spaces,

seen in Fig. 1, at the sides of the metal stirrup. A very small amount of current is then,passed through the transformer primary to induce a slight current in the stirrup as a closed secondary, slightly increasing the heating of the refractory abovethat received by 't-in the oven. Either before or after this slight heating of the form (secondary) the intermediate material may be removed or destroyed (as by a flame) or it may be melted out as in .the case of wax or a low melting alloy, or it may be squeezed out as in the case of wax. ,The melting may be done by the heat from the form' (secondary). Preferably after the stirrup and lining zinc or a starting charge may be poured in the wax 22 on the outside. For the exhave been heated in this way moltenheat of the stirrup may at the same time be made to maintain the zinc in molten condition and the molten zinc or starting charge yields with the expansion of the stirrup avoiding breakage of the refractory whileat the same time heating not only the lower part of the channel where the metal stirrup is of. full sizebut maintaining either the molten zinc, or starting charge, or the material of the stirrup displacing it, in contact with the lining. The drying and sintering may be accomplished by the heating of the form without a molten charge but not quite so advantageously. as with the aid of the molten metal.

After the current has been kept on in this manner for a sufficient length of time, where molten zinc has been used or where no molten metal has been poured in, the liquid starting char e is poured in and the furnace is started wit out the same risk of breakin the stirrup and interrupting the flow 0 secondary current by reason of the melting of the stirrup before there is a sufiicient head of molten metal above it; and without risk of cracking the refractory material by expansion of the form orsstirrup. The stir rup finally melts and merges with the starting charge.

Where the starting charge is inserted directly upon the form, without intermediate use of molten zinc, the stirrup should be heated 'to a higher temperature before thev starting charge is, oured in than would be re uired before mo ten zinc is'inserted.

he outsidejwax and the intermediate material shown between the outer metal strips or bars in Figs. 69' take up transverse expansion of the metal. The wax, (inside "or outside) of course, would squeeze out with pressure and melts at a. low temperature. It is thus radially displaced by the expandin molten zinc or starting 0 arge. Wood com-.

presses slightly, enough to relieve the excover is 'ghly beneficial.

5 metal and by the the In order that the current carrying capacity of the upper part of the stirru may be reduced so as to make this the wea est part electrically and protect against interruption of the secondary circuit at some lower and less accessible point, I make the upper portion of my stirrup hollow, connecting by the straps as described. By this arrangement, too, the molten zinc or molten starting charge -fills in the groove across the bottom of the pool between the straps 25 and 26 and protects against interruption of the secondry circuit in case of melting of the straps at the top of the stirrup, automatically healing any gap threatened thereby.

It will be evident that my invention is not confined to channels within the space heneath the furnace nor even to those having dominant metal pools but is applicable to all forms wherein a solid form is desired, and where a yielding, destructible or removable filler member can be used to give room for an expansion of the solid form which would otherwise injure or break the furnace. The word filler is used herein to apply to the wax outer covering, the side strips and the intermediate material in the center between outer conducting strips in Figs. 6-9.

It will be evident that, as compared with the filler members or non-metallic part of the section, the metal partof the stirrup is a quasi-permanent part of my form and that the skeleton sides in Figs. 1 and 2 give room for expansion and when expanded, need not completely fill out the spaces within the side channels, 11. e., against the outer limiting walls, as the molten zinc, or other molten content .used will fill any space left either outside or inside the expanded skeleton side members. The molten zinc or starting charge also fills, to any depth desired, the space in 'the groove 27 within the bottom of the furnace defined by the spaced top straps or connections, covering the floor of this channeled groove and healing, as above stated, any break in the straps caused by their melting, preventing interruption of the secondary circuit.

It will be evident that the metal strips in Figs. 6-9 are both outer strips with re- Spect to the intermediate (middle) section, notwithstanding the wax outside of the strips, and that this arrangement is preferred instead of a metal center'and the use of the entire compressible or removable section of the form of outer strips in orderto bring the metal strips into more intimate engagement with the channel walls, reducing the extent of engaging surfaces of the wood or low-fusing metal, for example. Where the outer coating of wax is not very thick, as in my preferred use, heating of the metal soon brlngs the latter into substantial contact with the channel wall.

It will be evident that the manner of supporting the fillers upon the skeleton sides during the placing of the lining as well as the determination of the material to be used for the fillers and whether these shall be removed by destroying them in position or by withdrawing them or by squeezing them out or melting them out will depend upon the judgment of the operator, the shape of the stirrup, the accessibility of the channel parts from within the furnace and other factors which vary with the installation and the conditions under which it is placed.

It will also be evident that the temporary filler may be located either outside the main form or between parts thereof, and may act by virtue of its compressibility, its mobility under pressure, its fluidity when heated, its destructibility or its removability.

lVhat I claim as new and desire to secure by Letters Patent is 1. A form for outlining the channel path in an electric furnace having a cross section of different materials, one a conductor of electricity and the other adapted to occupy space during the placing of the'lining and to permit expansion of the conducting material into this space subsequently..

2. A form for outlining the channel path in an electric furnace having a cross section of difi'ering materials having different heat resisting capacities and one of them a constroyed at a temperature lower than themelting point of the conductor.

5. A form for outlining the channel path in an electric furnace having, in cross section, conducting material on the opposite sides and material of lowerconductivity in between.

6. A form for outlining the channel path in an electric/furnace having, in cross section, electrically conducting material on opposite sides of the center and an intermediate temporary filler therebetween.

7. A form for outlining thechannel path in an electric furnace having, in cross section, electrically conducting material on opposite sides of the center and temporary filling material between them and also outside of the electrically conducting material.

8. A form for outlining the channel path in an electric furnace havinga non-homogeneous cross section and of material and shape adapting to destruction of the form its cross section of high heat-resisting qualin an electric furnace having in cross sec tion an electrical conductor and a low melting point core therefor.

11. A form for outlining the channel path in an electric furnace, of wood having a hollow center and closed at the bottom.

12. A form for outlining the channel path in an electric furnace having a portion of ity and. a portion having cushioning functions or removalble therefrom.

13. A form for outlining the channel path in an electric furnace which in cross section has material on opposite sides of the center which does not extend to the center and suited thereby for destruction of the form to give place to the furnace metal.

14. A form for outlining the channel ath in an electric furnace containing a owmeltin -point alloy.

15. form for outlining the channel path in an electric furnace comprisinga stirrup and filler material therefor removable to allow expansion room for the stirrup.

16. A form for outlining the channel path in an electric furnacel having removablev filler members located in the position of Ion 'tudinal expansion of the form.

1? A form for outlining the channelpath in an electric furnace comprising a lower electrically conducting channel member and an upper electrically conducting skeleton connecting therewith to complete a secondary circuit 'in combination with temporary filling for the sides of the skeleton.

18. "A form for outlining the channel ath in an electric furnace comprising a ower metallic member, sides connected therewith and spaced top metallic connections between'the upper ends of the sides.

19. A form for outlining the channel pathin an electric furnace comprising a lower member of full cross section, sides connectedtherewith and spaced metallic connections between the sides at the top.

20. A form for outlining the channel path in an electric furnace comprisin a lower V-shaped metallic member, su tially parallel metallic skeleton sides and metallic in an electric furnace 0 connection at the top between the sides.

21-. A form for outlinin the channel path electrically conductin material and having its cross section 0 smallest area at the top to provide for interruption first at that point.

22. A form for outlining. the channel path I in an electric furnace of smaller size in form to full cross section than the cross section of the channel in combination with molten metal filling the space between the form and the inner channel walls.

23. A form for outlining the channel path in an electric furnace having a metallic member and also a more temporary non- I metallic member, each extendinglongitudinally throughout the length of the channel.

24. The method of forming an electric furnace channel which consists in providing an electric conductor extending the length of the channel and of less cross section than the channel at the sides in the direction of the longitudinal expansion of the channel, completing the cross section of the conductor for the initial formation of the channel, removing the additional 'material added, heating the conductor to dry out the channel and finally melting out the conductor.

25. The process of forming an electric furnace channel and protectin its sides from injury by expansion of the o mi which consists in constructing a part of the cross 4 section of the form ofyieldable, removable or destructible material to relieve from expansive strain and taking advantage of this capacity to permit drying out of the channel walls by heating the form.

26. The process of forming anelectric furnace channel lining which consists in ength of the channel having a part only of the cross section of the channel where it is desired to relieve the channel wall from strains due to expansion, providing a temporary filler to complete the form there to roviding a metallic member extending the full channel cross section, forming the channel wall bout the member and filler removing the temporary filler to permit expansion into the space occupied by it previously and heating the metallic member to dry and sinter the lining at the same time that molten metal is supplied in conjunction with the metal member.

' 27. The process of forming a channel lining which consists in providing a metallic member of full channel size throughout a portion of the contour to be formed, providing temp rary -fillers to complete the channel size throughout another portion thereof, placing the channel wall about the form,'removing the temporary fillers to permit expansion, heating the metallic form to dry and sinter the lining at the same time that molten metal is supplied to fill the space between the second portion of the channel and the channel walls, and ultimately melting out the metallic form. v

28. The process of formingl and drying the channel ;of an electric rnace which consists in forming a channel portion of full channel siz'e adapted to expand, connecting the ends of this channel portion by a me-, talli c skeleton smaller than the channel sec-' tion where expansion would take place, closing the top to form a closed metallic dircuit, using removable fillers to complete the channel slze in the skeleton portion, placing the channel wall about the form removing the fillers and passing induced electric current through the secondary path formed after removal of the fillers to dry and sinter the lining and ultimately melt the same.

29. The process of drying a lining and starting an electric furnace which consists in using -a metallic form for the furnace channel throughout the length of the channel and skeletoned to permit expansion throughout a portion at least of its length, with. a removable filler for temporarily increasing the form to channel size 'in the skeleton portion, placing a lining about the form and filler, baking the lining and further drying the lining byinduced current through the form after removal of the filler, and in the presence of a molten char 0 of lower melting point than the metallic orm, t sinter the adjoining lining and maintain the charge molten.

30. The process of drying a lining and starting an electric furnace which consists in using a metallic form for the furnace channel throughout the length of the channel but not of the full channel cross section with a removable filler for temporarily increasing the form to channel size, placing a lining about the form and filler, baking the lining, further drying the lining by induced current through the form before or after removal of the filler, applying a molten charge to sinter the adjoining lining and maintain the charge. molten and ult1- mately increasing the induced current-to melt out the metal form.

31.*The process of drying a lining and starting an electric furnace which consists in using a metallic form for the furnace channel throughout the length of the channel skeletoned to permit expansion throughout a portion at least of its length, with a removable filler for temporarily increasing the form to channel size in the skeleton portion, placing a lining about the form and filler, baking the lining, further drying the lining by induced current throu h the form after removal of the filler and 111 the resence of a molten charge to sinter the ad oinin lining and ultimately increasin the in need current to--melt out the metal orm while the form is subjected to a substantial hydraulic 6 head of molten metal.\

32. The process of forming a channel lin-- ing for an electric furnace and startin the furnace which consists in providing a c osed circuit metallic channel form, throughout the length of the'channel and reduced in r section at the sides to provide for expansion, filling out by removable material to the size of the channel at the reduced portion of the form, placing a lining about the ,form, removing the removable portion of the composite form, partially drying the refractory lining, passing electric current through the form to sinter the refractory lining, providing a head of molten metal over and in fluid communication with the form and increasing the current through theform to melt it.

33. The method of starting an electric furnaceof channel type which consists in providing a metal form within the channel having apart of less cross section than the channel, leaving expansion room, placing a lining about the form, filling in a out said part with molten metal and passing electric current through theform to melt the form and start the furnace.

34. The method of starting an electric furnace of channel type which consists in providing a metal form within the channel having a part of less cross section than the channel, leaving expansion room, placing a lining about the form, filling in about said part with molten metal having a lower melting point than the metal of the form and passing electric current through the form to sinter the lining and maintain the metal of lower melting point in molten condition. 3

35. The method of starting an electric furnace of channel type which consists in providing a metal form within the channel having a part of less cross section than the channel, leaving expansion room, placing a lining about the form, filling in about said part with molten-metal having a lower melting point than the metal of the form, passing electric current through the form to sinter the lining and maintain the metal of lower melting point in, molten condition, providing a fluid head of molten metal above 110 the form and in fluid communication therewith and increasing the current through the form to melt the form.

36 The process of starting an electric furnace of channel type which consists in pro- 115 viding a metal form within the channel, placing a lining about the form, pouring in communication therewith molten metal having a melting point below that of the metal form,

heating the form by electric current to raise its temperature below its melting point but above that of the molten metal, supplying a head of molten metal of a higher melting point than the first molten metal and increasing the electric flow through the form 1 to melt it whiles'ubjecting it to the pressure due to said head.

' 37 The method of starting an electric furnace of channel type which consists in providing a metal form for the channel,

placing pressure a lining about the form, applying to the form by a head of molten ion therewith and meltin the form by electric current while it is 5 su ject to the head of molten metal.

" 38. The method of starting anelectric furnace of channel type which consists in providing a metal placing a lining) y passing an electric cur- 10 the metal form form within thechannel, about the form, heating rent through it, applying pressure to said form by a head of molten material and increasing the flow of electric current throu h the form to melt it while it is subject to the head of molten metal.

J. 'LUTHERIA KAUFFMAN, VWM. STEELL Jacxson. 

